ENS 51181
ENS Event | |
|---|---|
04:00 May 1, 2015 | |
| Title | Part 21 Report - Deviation in Nozzle Modeling Internal Reports |
| Event Description | The following was received via facsimile:
[This report pertains] to a deviation in a basic product (EPRI nozzle modeling internal reports) supplied by EPRI (Electric Power Research Institute) regarding Westinghouse Pressurizer Head Nozzle Inner Corner Region Ultrasonic Inspections. EPRI will complete all evaluation efforts and provide a determination of reportability in accordance with 10 CFR Part 21 no later than July 24, 2015. EPRI has conducted an evaluation to the basic product's actual use and determined that the ASME examination volume coverage for at least one of the pressurizer nozzles has changed and is now 90 percent or less. A 90 percent threshold is required by ASME Boiler & Pressure Vessel Code,Section XI. Design inputs used in EPRI modeling for ultrasonic scanning coverage for nuclear safety related component nozzles may have been inaccurate. In some cases, the upper and lower heads of Westinghouse pressurizers can be offset from the center of each nozzle (spray, safety, relief, surge). This offset results in a change in the thickness of the pressurizer head as compared to an on-axis pressurizer head with the same radial dimensions. Some of the computer models EPRI used to describe these pressurizer heads did not account for an increase in the thickness due to these offsets. As a result, in some cases the ultrasonic inspection parameters produced by these computer models may have produced inaccuracies in the examination volume coverage calculations. In the case of a basic component which contains a defect or falls to comply, the number and location of these components in use at, supplied for, being supplied for, or may be supplied for, manufactured, or being manufactured for one or more facilities or activities subject to the regulations in this part. Utility Name/Plant Name Exelon Corporation / Ginna First Energy Nuclear Operating / Beaver Valley 1 Entergy / Indian Point 2 Entergy / Indian Point 3 Pacific Gas & Electric Co. / Diablo Canyon Unit 2 Dominion Generation / North Anna EPRI has reviewed the pressurizer upper and lower head drawings for the nozzles that it has modeled and determined if these offsets are present. For those cases that are potentially affected EPRI has recalculate the new examination volume coverage for the nozzle inspection detection techniques and provided this information to the corresponding licensees. EPRI staff shall develop a matrix or table to better define the necessary design inputs for computer modeling of nozzles. This should also include a question to the utility regarding any obstructions or thickness changes which would impact the ultrasonic inspection parameters. EPRI staff shall improve its documentation for review and approval of design inputs for computer modeling. Consideration shall also be given to including a review of design inputs by the member along with an acknowledgement from the member that the design inputs are appropriate for use. EPRI staff shall consider methods of including additional conservatism to the modeling results to better accommodate changes which may be observed in the field. The project quality plan and quality project instruction shall be updated as necessary to accommodate or clarify these improvements. Completion commitment date - 10/27/2015. The coverage calculations indicated in the notification letters would likely increase if the EPRI modeled scan plans are exceeded and or if additional inspection angles were implemented. Conversely, these coverage calculations would likely decrease if physical field limitations prevented the ultrasonic probe from executing the EPRI modeled scan pattern. It is on this basis that recipients of this letter must evaluate the condition pursuant to 10 CFR Part 21.21 to determine if it could represent a substantial safety hazard reportable under 10 CFR Part 21. Potentially affected US plants include Ginna, Beaver Valley Unit 1, Indian Point Units 2 and 3, Diablo Canyon Unit 2, and North Anna.
As part of the evaluation, EPRI [Electric Power Research Institute] performed an 'extent of condition' review. During the course of the review, EPRI found that the above described deviation also affected EPRI nozzle modeling internal reports supplied by EPRI (Electric Power Research Institute) regarding Westinghouse Steam Generator Primary Nozzles. After conducting the 'extent of condition' review, which included recalculation of the modeling data, EPRI concluded that there were no other known reportable conditions associated with this deviation. EPRI has completed all evaluation efforts and issued reportability notification letters in accordance with 10CFR Part 21 within the respective reporting timeframes. Notified the R1DO (Kennedy), R2DO (Musser) and R4DO (Gepford) and Part 21 Group (via email). |
| Where | |
|---|---|
| Electric Power Research Institute Charlotte, North Carolina (NRC Region 1) | |
| Organization: | Electric Power Research Institute |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
| Time - Person (Reporting Time:+1331.67 h55.486 days <br />7.927 weeks <br />1.824 months <br />) | |
| Opened: | Tracy Wilson 15:40 Jun 25, 2015 |
| NRC Officer: | Dong Park |
| Last Updated: | Jul 24, 2015 |
| 51181 - NRC Website
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Electric Power Research Institute with 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 511812015-05-01T04:00:0001 May 2015 04:00:00
[Table view]10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Report - Deviation in Nozzle Modeling Internal Reports 2015-05-01T04:00:00 | |